AK2358F Datasheet, PDF (5/26 Pages) Asahi Kasei Microsystems – Base-band LSI for Europian Cordless Telephones(CTI, CTI+)

ASAHI KASEI
[AK2358FI
I
Circuit Configuration
I
Block
AMP1
TXHPF
Compressor
Pre-emphasis
Scrambler (Tx)
Limiter
Splatter filter
MSK modulator
AMP2
RXLPF
RXHPF
De-emphasis
De-scrambler (Rx)
Expander
Function
The operational amplifier for voice signal transmission gain
adjustment and for the filter to eliminate aliasing noise by the
SCF(switched capacitor filter) in the following stage. Use an
external resistor and capacitor to set the gain less than 30dB and
the cut-off frequency to about 10kHz.
The SCF circuit to eliminate the low frequency component less
than 300Hz from the transmission voice signal.
The circuit to compress the amplitude of the transmission voice
signal.
The circuit to emphasis the high-frequency component of the
transmission voice signal to improve the S/N of the modulation
signal.
The circuit to inverse the transmission voice spectrum in regard
to the carrier frequency. Carrier frequency can be selected from
two frequencies by KEY. PCONT select to use the scrambler or the
pre-emphasis circuit.
The amplitude-limiting circuit to suppress the frequency deviation
of the modulation signal. The limitation level can be adjusted by
applying a DC voltage to the LIMLV pin. If the LIMLV pin is open,
the default limitation level is applied.
The SCF circuit to eliminate the high frequency component higher
than 3.4kHz from the limiter output signal or the MSK u odulator
signal.
The circuit to generate a 2400bps MSK signal according to the
received digital signal logic from the TDATA pin.
The operational amplifier to adjust the reception demodulation
signal gain and for the filter to eliminate the aliasing noise of
the SCF in the following stage. Set the gain to less than 30dB
and the cut-off frequency to about 10kHz by external resister and
capacitor.
The SCF circuit to eliminate the high frequency component higher
than 3.4kHz from the limiter output signal or the MSK modulator
signal.
The SCF circuit to eliminate the low frequency component lower
than 300Hz from the reception voice signal.
The circuit to de-emphasis the emphasized signal by pre-emphasis
circuit.
The circuit to re-inverse the spectrum of the scrambled receiving
voice signal respect to the carrier frequency. Carrier frequency
can be selected from two candidates by a KEY. The de-scrambler(Rx)
or ~he reemphasis circuit can be selected by PCONT.
‘the circuit to expand the signal amplitude compressed by the
compressor.
0152-E-00
“4-
1996, 12